As part of its operating agreement with the state, Dow for months
has been collecting as many as 3,000 sediment samples for dioxin testing
in and around 6.5 miles of the river, beginning at Midland's Tridge. A
full report on the testing is expected in February, but preliminary
samples have turned up levels of contamination as high as 87,000 parts
per trillion in the river channel and higher-than-expected levels within
riverbanks. The state's action level is 90 parts per trillion, but of
511 sample results released, nine showed levels higher than 10,000 ppt
and four higher than 50,000 ppt.
"That raised some eyebrows," said Dow spokesman John Musser.
The new information also has caught the attention of the U.S.
Environmental Protection Agency and the state Department of
Environmental Quality. The agencies are in discussion with Dow about
short-term actions that will prevent human exposure to the contamination
and further river contamination from eroding banks.
"Everybody is in agreement Dow will go and remove the 87,000. To
the extent we address other levels has not been determined," Musser
Action is likely to include "dry dredging," which refers to a
technique in which the river flow is interrupted briefly so that
sediment can be dug out, Musser said. Material removed from the river
likely will be taken to Midland's municipal landfill. The company is in
talks with the City of Midland to firm up that plan.
But before there is any digging, the company must find out how
large the highly contaminated areas are. "We could have gotten it in the
sample jar," Musser said. "It could be that small, or it could be as big
as a football field."
To find out, Dow will be sampling areas around the site where the
original elevated samples were found.
Along with identifying areas for cleanup, Dow and the DEQ also
have to reach an agreement on what level of contamination will trigger
action. Previous hotspots under discussion for possible cleanup ranged
from 8,000 ppt to around 20,000 ppt. Until now, those were the highest
Neither Musser or the DEQ is hinting at what the interim action
level might be. "It can't be a number pulled out of a hat," Musser said.
"It has to be science-based."
And while Dow has agreed to the work, Musser stressed it's not
because the company believes the levels pose a health risk.
"In the context of the Garabrant study, we don't think it
represents an imminent health hazard," Musser said, speaking of the
University of Michigan exposure study released in August.
That study showed that people living on or near contaminated soil
have higher levels of dioxin in their blood based on their residency,
but also showed the majority of dioxin exposure comes from the national
food supply and is related to factors such as age and sex.
But the DEQ is not as confident and does have concern about human
exposure and contact and potential risk to wildlife. "We think it is a
potential public health and environmental health issue," said Deb
MacKenzie-Taylor, toxicologist for the DEQ's Waste and Hazardous
Since informing the DEQ of the data last month, Dow has installed
additional signs near the river by its Midland plant, warning river
travelers of potential hazards. The findings also have led to an
agreement that more testing will be conducted in residential areas of
the Tittabawassee River flood plain.
"It helped us insist on that, and Dow to agree on that," said DEQ
Geologist Allan Taylor.
That tesing will come in the next field season. In the meantime,
Dow is in the process of applying for permits to conduct the river work.
Weather will be a factor, and come spring, so will walleye spawning,
which can't be interrupted for the project.
Both Dow and the DEQ say they want to get to work but proceed
with caution. "We want to move as quickly as possible," Taylor said. "We
also want to move carefully so we don't end up causing a bigger
That's a concern for Midlander and grass-roots group Midland
Matters founder Bill Egerer. He disagrees with efforts to clean up
dioxin, saying he wonders if doing so will cause more harm than good. "I
would like to see the study that shows digging it up is better than
leaving it there," he said.
But environmental groups are encouraged by the potential for
action. "I think the numbers are horrifying," said Terry Miller of the
Bay City-based Lone Tree Council, which has been pushing Dow and the
state to clean up previously known hotspots, at least.
"It confirms the need to address these things and address them
upstream before they get downstream," he said. "The DEQ has got to
stiffen its spine, and Dow's got to do the right thing."